Centrifuge rotor cover

ABSTRACT

There is disclosed a cover for a centrifuge rotor which is affixed thereto by being screwed onto the hub of the rotor. The cover is constructed in a manner to provide a depending skirt which seats against an upstanding rim of a rotor of a centrifuge. This cover is constructed to seat tighter under the centrifugal forces encountered whereby a portion of the skirt is urged outwardly and down against the seat on the rim. The cover is also designed to have an annular well for collecting small quantities of overflow fluid. The cover is also consructed with a means to preliminarily provide communication between the outside and inside the rotor of the centrifuge in order to establish equilibrium therebetween prior to removal of the cover.

United States Patent [191 Romanauskas et al.

[ CENTRIFUGE ROTOR COVER [75] lnventors: William A. Romanauskas,

Southbury; Charles Paulsen, Newtown, both of Conn.

[73] Assignee: Ivan Sorvall, lnc., Norwalk, Conn. [22] Filed: Apr. 9,1973 [2]] App]. No.: 349,402

[52] US. Cl. 233/27 [51] Int. Cl B04b 1/00 [58] Field of Search 233/1 R,3, 4, 8, 27, 28, 233/32, 44

[56] References Cited UNITED STATES PATENTS 3,244,363 4/1966 Hein 233/283,430,849 3/1969 Gibson et al 233/] R June 25, 1974 PrimaryExaminer-George H. Krizmanich Attorney, Agent, or Firm-Eric P. Schellin;Martin P. Hoffman 5 7 ABSTRACT There is disclosed a cover for acentrifuge rotor which is affixed thereto by being screwed onto the hubof the rotor. The cover is constructed in a manner to provide adepending skirt which seats against an upstanding rim of a rotor of acentrifuge. This cover is constructed to seat tighter under thecentrifugal forces encountered whereby a portion of the skirt is urgedoutwardly and down against the seat on the rim. The cover is alsodesigned to have an annular well for collecting small quantities ofoverflow fluid. The cover is also consructed with a means topreliminarily provide communication between the outside and inside therotor of the centrifuge in order to establish equilibrium therebetweenprior to removal of the cover.

8 Claims, 4 Drawing Figures PATENTEDJUN251974 1 3319.111

SHEEI 1 BF 2 F/GJ; 1 i

PATENIEDJUN25|9T4 819,111 I sum 2 or 2 FIG. 3. A

CENTRIFUGE ROTOR COVER BACKGROUND OF THE INVENTION During the last fewyears chemical laboratory procedures, especially with regard to clinicalchemistry, have demanded that centrifuges be capable of rotating at evergreater speeds. As a result, an ultra-centrifuge has been developedwhich employs a rotor normally used at revolutions per minute in anexcess of 60,000. Of course, such rotors are carefully constructed toprovide accurate balance and good strength integrity so that the rotordoes not fly apart under the terrific centrifugal forces built up as itis rotated. The centrifuge tubes employed in such ultracentrifuges arecapped and sealed after the liquid contents are added to the tubes. Inmany cases it is necessary to insure a sealed environment within therotary even though the tubes themselves have been sealed. The tubes aresealed at ambient atmospheric pressure as is the rotor itself by meansof a centrifuge rotor cover. However, the rotor is operated in a vacuum.

Underthe terrific forces created, the caps may not seal as well asdesired and some of the liquid contents therein may gradually creep outof the tube. To retain the liquid that may be spilled from the tubesduring centrifugation a rotor must have a cover. As the tubes maycontain liquids which are radioactive or which possess dangerousbiological materials, it will be apparent that serious problems couldfollow if there would be leakage beyond the confines of the rotor. Asthe rotor is in a vacuum chamber, the vacuum pump would remove anyspilled materials from the chamber and expell at least some of suchmaterials into the laboratory atmosphere. A well working cover thatperforms its task even though being subjected to considerablecentrifugal forces and hydrostatic forces from accumulated tube leakageis the subject matter of the present invention.

SUMMARY OF THE INVENTION The cover of the present invention has anoverall disc-like configuration. A downwardly depending skirt isdesigned to have a portion thereof seat itself internally with respectto an upwardly extending peripheral rim on the rotor. The cover has aconcentric aperture. A core is slidably positioned in the aperture. Thecore has a portion of sufficient diameter whereby it fits relativelysnugly within the aperture. The core has a re cessed shoulderapproximately flush with the upper surface of the cover directlyassociated therewith. The core has an upwardly extending portion aboutwhich is positioned a hollow outer shell. The shell is designed so thata downwardly facing surface bridges the shoulder of the core and aportion of the surface of the cover. The outer shell and core near theupper portion thereof are held together by a common acting handle. Theother end of the core possesses means whereby it is screwed to the hubof the rotor. As the cover is screwed to the hub, the outer shell andcore which has an O-ring move slightly relative to the cover whereby asealing action occurs as the O-ring is squeezed between the core andinside the aperture of the cover. This sealing action occurs at the endof the operation to tighten the cover. Conversely, when the cover is tobe removed the core and outer shell by first being loosened makes itpossible to establish gas pressure equilibrium between the atmosphereand the space in the rotor.

Of considerable importance to the instant invention is the fact that thecover has a relatively thinned portion intermediate the aperture and theouter periphery of the cover. As the centrifugal forces exertthemselves, the skirt will tend to be thrust radially outwardly anddownwardly to seat itself more securely against the rim which is moreresistant to enlargement.

Additionally, the skirt is provided with an annular well internally withrespect to the skirt whereby most of the liquid which may escape fromthe centrifuge tubes and creeps upwardly will be captured by the welland the subsequent hydrostatic pressure will be self containedminimizing any tendency to lift the lid.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of arotor of an ultracentrifuge with the cover of the present inventionattached thereto.

FIG. 2 is a cross section taken along line 2-2 of FIG. 1 with the covernot yet completely secured.

FIG. 3 is a similar view as in FIG. 2 with the cover completely secured.

FIG. 4 is a close-up cross-sectional view to provide a detail view ofthe manner of seating the cover of the present invention with respect toan upstanding annular rim of the rotor of the centrifuge.

DETAILED DESCRIPTION OF THE INVENTION Beginning with FIG. 1 the covershown, generally, by reference numeral 10, depicts the cover of thepresent invention. It will be noted that the cover is secured to a rotor11 of a centrifuge. The rotor is of the ultra-high speed type usuallymachined from a single metal block with fixed recesses designed toaccept specially constructed centrifuge tubes. These tubes are utilizedin a sealed tightly capped condition. More details with respect to thecentrifuge rotor can be gleaned from FIGS. 2 and 3. The recesses 12 forthe centrifuge tubes can be seen.

Again, with particular reference to FIGS. 2 and 3, the cover 10 includesa disc means having an annular portion. The annular portion has acentrally located aperture 14. The annular portion terminates in adownwardly depending annular skirt 15. It will be seen that the annularportion has a flat section 16 facing upwardly. The other or underside 17is inclined upwardly. As the two surfaces, i.e., section 16, andunderside 17 are not in the same plane the annular portion will tend todecrease in thickness and at 183 assumes its thinnest dimension. Theflat section 16 terminates at 18 into an upwardly extending radialportion 19. Portion 19 will be seen to be somewhat thicker than at 18.

The depending skirt 15 has an outwardly facing shoulder 21, as seen ingreater detail in FIG. 4. The shoulder includes a downwardly facing flatsurface 22. The skirt 15 is inclined inwardly to form portion 23. Anoutwardly facing peripheral groove 24 is located in portion 23. Thegroove 24 is adapted to accommodate 0- ring 25. The O-ring will be seento be in confrontation with the internal portion of the rim 26 of thecentrifuge rotor 11. More about this will be stated below.

Within the aperture is cylindrically shaped core 30. The portion 31constituting a first portion of the core is designed to fit slidably butrather snugly within the aperture. The outwardly extending periphery hasan annular groove 32 into which is fitted a suitable O-ring 33. Theaperture 14 has a lower wider diameter portion so that the aperture 14is somewhat larger at the bottom than at the top. Near substantially thebottom of the portion 31 of the core is an outwardly radially extendingflange 35. The flange 35 enlarges the lower part of the core to anextent whereby it cannot be removed upwardly from its position in theaperture.

The core extends upwardly beyond the plane of the upper flat surface ofsection 16 to form a second portion. The core has a shoulder 36 with aflat upwardly facing section approximately in the same plane as section16. An outer shell 38 having a bore encompasses the remainder of theupwardly extending core. It has a downwardly facing recess 39 adapted tobridge the shoulder 36 and a portion of section 16. A peripheraldownwardly extending flange 53 forms one wall of the recess. The flangeis adapted to fit into annular groove 54in section 16. An annular washer40 is positioned in the recess 39 and the upwardly facing section andsection 16. The washer 40 acts to prevent wear.

The upper part of the outer shell and the core therein are rotated by ahandle 41 which extends radially therefrom. It is positioned in a bore42 normal with respect to the axis of the core. The handle 41 is also inalignment with bores 43 and 44 in the outer shell 38. The handle isretained in position by a set screw 45.

The portion 31 of the core has an internally threaded recess 47 adaptedto receive a suitably threaded male member 48, constituting the hub ofthe rotor. In order to secure the cover of the present invention thecore is screwed onto the hub of the rotor. As the core is tightened theouter shell moves downwardly with the core. The annular portion 13 is,of course, positioned on the rim of the rotor at its outer peripheralextremity. The part adjacent the aperture 14 is between the outer shelland the flange 35 of the core. From FIG. 2 it will be seen that the coreand outer shell are withdrawn from the annular portion 13 to the extentpermitted by the cooperation of the flange 35 and the widened portion ofaperture 14. With the core and outer shell withdrawn the O-ring 33,thereby providing a gaseous communication with respect to one side ofthe cover to the other. When the cover is screwed onto the rotor thecore and outershell are screwed onto the rotor therewith carrying theannular portion to a sealing condition.

In unscrewing the cover the opposite relative movement occurs so thatthe core and outer shell recedes from its sealing engaging position toprovide pressure or vacuum relief to the space in the rotor.

Not mentioned before, is the ingenious annular well 50 internally aroundthe skirt. As this is the furthennost space from the axis of the coverany liquid escaping from the recesses 12 of the rotor and finding itsway into the internal spaced defined by the cover will become segregatedin this well.

As was stated heretofore the rotor is fabricated of high strength metalmaterials. Likewise, the cover of the present invention should beconstructed of similar materials as the cover is subjected to the sameenormous centrifugal forces as the rotor when the centrifuge isoperated.

What is claimed is:

l. A cover for a centrifuge rotor comprising a substantially disc means,said disc means having a downwardly depending skirt substantially alongthe periphery thereof, said disc means having a centrally positionedcircular aperture, a cylindrical core means, said core means having afirst portion adapted and constructed to fit slidably relatively snuglywithin said circular aperture, said core means having a second portionabove said first portion which has a diameter less than the diameter ofsaid first portion thereby forming a shoulder on said core means, anouter shell means, said outer shell means having a bore adapted andconstructed to slidably encompass said second portion of said coremeans, the disc means having an upper radially extending flat surfaceportion radiating directly from said aperture and a concomitantly lowerupwardly inclined radially extending surface whereby the disc decreasesin thickness, the said upper flat surface tenninating in an upwardlyradially extending portion having an increasing thickness, the saidupwardly radially extending portion substantially terminating with saidskirt, the said skirt having a downwardly facing shoulder along theouter periphery thereof, said skirt beginning at said shoulder having aninwardly inclined terminal portion adapted to rest against an annularseat on a centrifugal rotor, the outer shell having a thicknesssufficient to bridge the said first portion and the said upper flatsurface, said core means having means at the bottom portion thereof forscrewing said cover onto cooperating means on a rotor of a centrifuge,said core means and said outer shell means having joint handle means attheir respective upper portions thereof.

2. The cover for a centrifuge according to claim 1 wherein an annularwasher means is positioned between the said outer shell bridging thesaid frrst portion and the said upper flat surface.

3. The cover for a centrifuge according to claim 1 wherein the means forscrewing the cover to the rotor of a centrifuge includes an internallythreaded recess at the bottom of said core means adapted to be threadedonto a threaded male portion of a rotor.

4. The cover for centrifuge according to claim 1 wherein the said handlemeans radially extends through said core means and said outer shellmeans.

5. The cover for a centrifuge according to claim 1 wherein the firstportion of said core means has an outwardly radially extending flangeand said aperture has a lower wider diameter portion adapted andconstructed to engage said flange whereby the said core means isrestrained from parting from said disc means.

6. The cover for a centrifuge according to claim 5 wherein an annularwasher means is positioned between the said outer shell bridging thesaid first portion and the said upper flat surface.

7. The cover for a centrifuge according to claim 6 wherein the means forscrewing the cover to the rotor of a centrifuge includes an internallythreaded recess at the bottom of said core means adapted to be threadedonto a threaded male portion of a rotor.

8. The cover for a centrifuge according to claim 7 wherein the saidhandle means radially extends through said core means and said outershell means.

1. A cover for a centrifuge rotor comprising a substantially disc means,said disc means having a downwardly depending skirt substantially alongthe periphery thereof, said disc means having a centrally positionedcircular aperture, a cylindrical core means, said core means having afirst portion adapted and constructed to fit slidably relatively snuglywithin said circular aperture, said core means having a second portionabove said first portion which has a diameter less than the diameter ofsaid first portion thereby forming a shoulder on said core means, anouter shell means, said outer shell means having a bore adapted andconstructed to slidably encompass said second portion of said coremeans, the disc means having an upper radially extending flat surfaceportion radiating directly from said aperture and a concomitantlY lowerupwardly inclined radially extending surface whereby the disc decreasesin thickness, the said upper flat surface terminating in an upwardlyradially extending portion having an increasing thickness, the saidupwardly radially extending portion substantially terminating with saidskirt, the said skirt having a downwardly facing shoulder along theouter periphery thereof, said skirt beginning at said shoulder having aninwardly inclined terminal portion adapted to rest against an annularseat on a centrifugal rotor, the outer shell having a thicknesssufficient to bridge the said first portion and the said upper flatsurface, said core means having means at the bottom portion thereof forscrewing said cover onto cooperating means on a rotor of a centrifuge,said core means and said outer shell means having joint handle means attheir respective upper portions thereof.
 2. The cover for a centrifugeaccording to claim 1 wherein an annular washer means is positionedbetween the said outer shell bridging the said first portion and thesaid upper flat surface.
 3. The cover for a centrifuge according toclaim 1 wherein the means for screwing the cover to the rotor of acentrifuge includes an internally threaded recess at the bottom of saidcore means adapted to be threaded onto a threaded male portion of arotor.
 4. The cover for centrifuge according to claim 1 wherein the saidhandle means radially extends through said core means and said outershell means.
 5. The cover for a centrifuge according to claim 1 whereinthe first portion of said core means has an outwardly radially extendingflange and said aperture has a lower wider diameter portion adapted andconstructed to engage said flange whereby the said core means isrestrained from parting from said disc means.
 6. The cover for acentrifuge according to claim 5 wherein an annular washer means ispositioned between the said outer shell bridging the said first portionand the said upper flat surface.
 7. The cover for a centrifuge accordingto claim 6 wherein the means for screwing the cover to the rotor of acentrifuge includes an internally threaded recess at the bottom of saidcore means adapted to be threaded onto a threaded male portion of arotor.
 8. The cover for a centrifuge according to claim 7 wherein thesaid handle means radially extends through said core means and saidouter shell means.